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M Meunier

Publications and source records attributed to M Meunier.

At least 55 records · Page 3Linked to original sources
PubMed1993

Polyhedral microcalcifications at mammography: histologic correlation with calcium oxalate.

Pathologists have associated calcium oxalate dihydrate (weddellite) in breast biopsy specimens with benign or borderline lesions and rarely with malignancy. These microcalcifications may have a polyhedral shape in histologic specimens owing to their crystalline structure. A retrospective radiologic-histologic correlation study was performed on 300 clusters of microcalcifications to determine if microcalcifications with a polyhedral shape could be found at mammography. In 19 cases (6.3%), polyhedral microcalcifications (PMs) were detected by two radiologists. In 12 of these 19 cases, weddellite crystals were found in the histologic specimen under polarized light; in seven cases, no calcification was found. Although rare, PMs can be found at mammography by radiologists aware of their existence. They are due to weddellite crystals and in this series were associated with benign disease in 89% of cases. Prospective studies are required to determine the frequency of PMs on screening mammograms and to evaluate their negative predictive value.

Breast↗
PubMed1993

Effects on visual recognition of combined and separate ablations of the entorhinal and perirhinal cortex in rhesus monkeys.

Performance on visual delayed nonmatching-to-sample was assessed in rhesus monkeys with combined and separate ablations of the perirhinal and entorhinal cortex, as well as in unoperated controls. Combined (i.e., rhinal cortex) lesions yielded a striking impairment on this task, one almost as severe as that seen after combined amygdalohippocampal removals that included some of this subjacent cortex (Mishkin, 1978; Murray and Mishkin, 1984). Ablations of the perirhinal cortex alone produced a deficit nearly as severe as that found after rhinal cortex lesions, whereas ablations of the entorhinal cortex alone produced only a mild deficit. Contrary to the conclusion from an earlier study (Murray and Mishkin, 1986), the present results demonstrate not only that damage limited to the rhinal cortex is sufficient to produce a severe loss in visual recognition, but also that such damage leads to a far greater loss than damage to any other single structure in the medial part of the temporal lobe.

Animals↗
PubMed1992

Mammographic features of 455 invasive lobular carcinomas.

Of 6,009 cases of breast cancer studied, 455 (7.6%) were invasive lobular carcinoma (ILC); 341 of these (75%) were pure ILC and 114 (25%) were ILC mixed with ductal forms. The mammographic features were compared with those of the 5,554 other breast carcinomas. Pure ILCs were less frequently round (1% vs 11%) and more frequently spicular (28% vs 23%) or with architectural distortion (18% vs 6%) than the other breast carcinomas. Microcalcifications were less common (24% vs 41%) and retraction of the skin (25% vs 21%) and nipple (26% vs 17%) was more common in pure ILC than in the other breast carcinomas. When complementary magnification views were obtained, only 50% were helpful in diagnosis of ILC while 75% were helpful in diagnosis of other breast carcinomas. Malignancy was less frequently diagnosed in ILC (57%) than in the other breast carcinomas (64%). The results were intermediate in the mixed ILC group.

Adult↗
PubMed1992

Influence of season of birth on onset of gonadotrophic and ovarian functions in young doe hares (Lepus europaeus).

The pituitary and ovarian responses to a monthly i.v. injection of 5 micrograms luteinizing-hormone-releasing hormone (LHRH) were studied in three groups of young doe hares, born in January-February (group I), in April (group II) or at the end of the breeding season (August-September, group III). The LHRH injection was always followed by a release of LH and progesterone, which did not differ among the three groups at 3 months of age. The pituitary and ovarian responses to LHRH increased gradually from the age of 3 months in groups I and III and from the age of 9 months in group II. One female of the ten born in January-February ovulated and reached puberty in June, at the age of 4 months, but with a weak pituitary response. The females born in April displayed a seasonally delayed puberty, at 9 months of age (two of five females ovulated in the next January). Four of the five females born at the end of the breeding season ovulated after LHRH when 5 months old (in February), with a full pituitary-ovarian response. The low pituitary response of group I in June-August, even if 10-20% of females ovulated after LHRH, suggests a need for a period of short days. Then, the most favourable conditions for the hare to reach puberty would be a period of short decreasing daylengths during the fall, followed by increasing daylengths after the winter solstice.

Age Factors↗
PubMed1992

[Therapeutic evaluation of Mormoiron attapulgite in acute diarrheas of infants and children. A multicenter study in controlled liberal practice versus placebo in 113 patients].

A placebo-controlled multicenter study was carried out to evaluate the effectiveness and safety of Actapulgite in infants and children with acute diarrhea. One hundred and thirteen patients, with a mean age of 28 months, were enrolled by pediatricians in the office. As recommended during acute diarrhea, the dosage of Actapulgite was doubled during the first three treatment days (2 to 4 packets a day according to the patient's weight), and reduced by half thereafter. The main effectiveness criteria was passage of the first normally formed stool, which denotes normalization of intestinal transit time. The first normally formed stool was recorded after two days of treatment with Actapulgite and was followed, on the next day, by a second normal stool, denoting complete recovery. The greater effectiveness of Actapulgite as compared with the placebo was demonstrated by the fact that both the first and the second normally formed stools were passed one day earlier with the active treatment (p = 0.01 and p = 0.002, respectively). In addition, resumption of a normal diet occurred significantly earlier with Actapulgite (4.4 days) than with the placebo (5.1 days). In addition to being effective, the study drug proved remarkably well tolerated. This study is especially valuable because of its office setting and the use of exclusively clinical criteria with a strict methodology.

Acute Disease↗
PubMed1991

Differential involvement of anterior and posterior cingulate cortices in spatial discriminative learning in a T-maze in mice.

The contribution of the anterior and posterior cingulate cortical areas to spatial learning and memory was examined in mice using a behavioral paradigm based on a spatial discrimination task in a T-maze. Multiple injections of small amounts of ibotenic acid were used to produce fiber-sparing lesions of either the anterior (ACC) or the posterior (PCC) cingulate area. Mice with ACC lesions, though learning the initial acquisition and first reversal of the discrimination at about the normal rate, were impaired during the subsequent four reversal sessions. In contrast to control mice, they failed to improve their performance from the first to the last session. Nevertheless, when later required to repeatedly learn the same discrimination over several days (repetitive testing), animals with ACC lesions no longer exhibited any learning deficit. The converse pattern of results was found in mice with PCC lesions. These animals performed much more poorly than control animals during the acquisition and first reversal of the discrimination, but displayed remarkable improvement over the subsequent four reversal sessions, gradually overcoming their initial impairment. However, when later submitted to repetitive testing, these animals again showed a substantial learning deficit. Neither ACC nor PCC cingulate lesions significantly affected the animals' retention capacities as measured by single test-trials over a 24-h interval. Yet, mice with PCC lesions were retarded in reversal learning after a long intersession interval (10 days), indicating that PCC, but not ACC, lesions did interfere with some long-term retention processes. These results imply that the ACC, as a part of the medial frontal cortex, may play a crucial role in temporally ordering a series of spatial responses, whereas the PCC seems to contribute to the formation and retention of each individual spatial response, probably by transmitting information from limbic structures such as the anterior thalamus and hippocampal formation to posterior neocortical association areas.

Adaptation, Psychological↗
PubMed1991

Time-dependent sequential increases in [14C]2-deoxyglucose uptake in subcortical and cortical structures during memory consolidation of an operant training in mice.

Previous results have suggested that memory processing may involve the sequential activation of subcortical and cortical structures. To study this phenomenon, we have examined the immediate (15 min) and delayed (220 min) metabolic changes produced in BALB/c mice by a partial training session in a bar-pressing appetitive task, using the [14C]-2-deoxyglucose (2-DG) relative glucose uptake method. These relative metabolic changes were compared to the ones produced in several control groups: untrained animals, sham-conditioned animals, overtrained animals, and animals forced to walk on a moving belt (immediate and delayed condition). Animals were given a single intrajugular injection (5 microCi) of 2-DG either 5 min before or 3 h (delayed condition) after the second training session. Forty minutes after the 2-DG injection, the animals were sacrificed and their brains processed for autoradiography. At the 15-min delay, a large 2-DG labeling increase was found in partially trained animals for various subcortical areas (septum, diagonal band, hippocampus, thalamus, and mammillary bodies) while a much smaller increase was found in four cortical areas (frontal, cingulate, parietal, and sensory motor cortices). At the 220-min delay, we observed a large 2-DG labeling increase in cortical (frontal, pyriform, and cingulate cortices) and subicular areas while a moderate 2-DG labeling increase was observed in entorhinal cortex and the diagonal band. These results show that, shortly after training, subcortical structures are preferentially activated while cortical structures are much less activated. Three hours later, at a time when retention performances have been shown to improve spontaneously in the same strain of mice and in the same task, cortical structures are highly activated.

Animals↗
PubMed1991

Pituitary and ovarian responses to luteinizing-hormone-releasing hormone during pregnancy and after parturition in brown hares (Lepus europaeus).

Female hares were given an i.v. injection of 5 micrograms luteinizing-hormone-releasing hormone (LHRH) between Days 7 and 19 (n = 21), 20 and 33 (n = 17) and 34 and 41 (n = 17) of pregnancy, and in the 3 days after parturition (n = 16). Whatever the stage of pregnancy, the LHRH injection induced a release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and an acute secretion of progesterone; these hormonal responses increased significantly during pregnancy, to reach values similar to those observed in nonpregnant, nonpseudopregnant females during the breeding season in the 3 days after parturition. However, the release of LH remained monophasic in pregnant and post-partum females, in contrast to the unmated females during the reproductive season, in which there was a biphasic profile. The proportion of ovulating females after LHRH treatment was approximately 60% at the beginning and end of pregnancy; and, after parturition, fell to 23% between Days 20 and 33. After Day 33, the pituitary response to LHRH was significantly higher in ovulating than in nonovulating females. At the beginning of pregnancy, 67% of females aborted after LHRH injection; after Day 20, the incidence of abortion decreased significantly and was 0% from Day 34. The amplitude and duration of progesterone secretion by the new corpora lutea resulting from ovulation after LHRH injection were similar to those of corpora lutea induced in nonpregnant females during the breeding season.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of ovariectomy at two periods of the year on LH and FSH basal concentrations and pituitary response to LHRH in the brown hare (Lepus europaeus).

In the brown hare, fertile mating takes place from the beginning of December to September. Seasonal variations of basal concentrations of LH and FSH, and pituitary response to a monthly i.v. injection of LHRH were studied in intact control females and in females ovariectomized during the seasonal anoestrus (OVX1) or during the breeding season (OVX2). In intact females, both basal and LHRH-stimulated LH levels showed an annual variation, with minimal values during anoestrus. During the breeding season, the LH response to LHRH exhibited a biphasic pattern. In contrast, there was no clear seasonal variation in basal and LHRH-stimulated FSH concentrations. After ovariectomy during anoestrus, basal LH remained low for 2 months and began to increase in December. After ovariectomy during the breeding season, LH basal concentrations increased within a few days after the operation. Thereafter, LH values remained high in both groups of females until September, and decreased significantly as in intact females. The pattern of LH release after LHRH remained monophasic in the two groups of ovariectomized females. In OVX1 females, the LH response increased as early as October, was maximum from December to April and decreased progressively until October. IN OVX2 females, the LH response decreased regularly after ovariectomy to a minimum in October. In the 2 groups of ovariectomized females, basal FSH concentrations and pituitary response to LHRH rose rapidly after ovariectomy and did not vary significantly thereafter. These results showed a direct central effect of season on the regulation of basal concentrations of LH, modulated by a negative feed-back of ovarian secretions during the breeding season. In intact hares, the enhanced LH response after LHRH during the breeding season was related to an acute positive effect of ovarian secretions. The regulation of FSH was less dependent on season and remained under a negative control of the ovary throughout the year.

Animals↗
PubMed1989

Quantitative [14C]2-deoxyglucose study of a functional dissociation between anterior and posterior cingulate cortices in mice.

We have previously shown that lesion of the posterior cingulate cortex (CCP) but not of the anterior cingulate cortex (CCA), produced learning and memory deficits. As a first evaluation of the functional anatomical basis of this dissociation, we used the quantitative [14C]2-deoxyglucose method and electrical brain stimulation to determine the functional connections of the CCA and CCP in mice. CCP stimulation (but not CCA stimulation) produced significant metabolic increases in the hippocampal formation and in the subicular complex. This result is consistent with the hypothesis that learning and memory deficits following CCP lesion may be due to the disruption of functional neural pathways between the CCP and hippocampal structures.

Animals↗
PubMed1989

[A severe form of juvenile polyposis coli].

The authors report a case of a life-threatening form of juvenile polyposis coli in a 7-year-old girl. The cure of this affection required a total coloproctectomy with ileoanal anastomosis.

Child↗
PubMed1988

Electrolytic but not ibotenic acid lesions of the posterior cingulate cortex produce transitory facilitation of learning in mice.

The rate of acquisition of 12 Hebb-Williams mazes was studied after restricted bilateral lesions of the anterior (ANT) or posterior (POST) cingulate cortex in BALB/c mice. In a first experiment, animals with electrolytic lesions were tested with the different mazes at 3 time intervals between 19 and 48 days after surgery. The rate of acquisition in POST-lesioned mice was observed to be facilitated at the 2 first time intervals (between days 19-22 and 32-35), but this effect was reversed (impairment) when the test was carried out between 45-48 days postsurgery; no significant effects were observed in ANT-lesioned mice. In a second experiment, the same behavioral paradigm was used in mice with restricted ibotenic acid lesions of the POST cingulate cortex. These lesions had no significant effects on the acquisition of the mazes. A third experiment was carried out to test if the postoperative delay itself contributed to the long latency of the impairment observed in Expt. I. No impairment of acquisition was observed when POST cingulate lesioned animals underwent their first learning session between 45-48 days after surgery; in contrast, a significant facilitation of the performance was observed at this time. These results suggest an involvement of the posterior cingulate cortex, and in particular the cingulum bundle, both in acquisition and long-term memory processes.

Animals↗
PubMed1988

In-vitro secretion of prolactin and growth hormone in the presence of melatonin by pituitary gland from mink kept under long or short days.

Mink anterior pituitaries were incubated in Medium 199 for up to 9 or 13 days. Biological activity of prolactin and GH was determined. Daily concentrations of prolactin and GH in the incubation medium were also measured by radioimmunoassay and radioreceptor assay. When females were kept under short days for several weeks before the experiment, a significant decrease in prolactin secretion by the anterior pituitary was observed as compared with that in females maintained under long days. In contrast, secretion of GH was not modified by the photoperiodic history of the animals. Pineal gland denervation by ablation of the superior cervical ganglia a few months before the experiment, or addition of melatonin to the incubation medium of anterior pituitaries from intact or ganglionectomized females, did not modify the secretion of prolactin and GH. The pituitary gland does not therefore seem to be a direct target site for melatonin in transducing the duration of daylength on the hypothalamo-pituitary axis.

Animals↗